Esters functional group

Two main viscosity additive families are used hydrocarbon polymers and polymers containing ester functional groups. 

LY311727 is an indole acetic acid based selective inhibitor of human non-pancreatic secretory phospholipase A2 (hnpsPLA2) under development by Lilly as a potential treatment for sepsis. The synthesis of LY311727 involved a Nenitzescu indolization reaction as a key step. The Nenitzescu condensation of quinone 4 with the p-aminoacrylate 39 was carried out in CH3NO2 to provide the desired 5-hydroxylindole 40 in 83% yield. Protection of the 5-hydroxyl moiety in indole 40 was accomplished in H2O under phase transfer conditions in 80% yield. Lithium aluminum hydride mediated reduction of the ester functional group in 41 provided the alcohol 42 in 78% yield. 

Under basic conditions, the o-nitrotoluene (5) undergoes condensation with ethyl oxalate (2) to provide the a-ketoester 6. After hydrolysis of the ester functional group, the nitro moiety in 7 is then reduced to an amino function, which reacts with the carbonyl group to provide the cyclized intermediate 13. Aromatization of 13 by loss of water gives the indole-2-carboxylic acid (9). 

Recent Developments in Chemical Deprotection of Ester Functional Groups," Salomon, C.J. Mata, E.G. Mascaretti, O.A. Tetrahedron, 1993, 49, 3691... 

In the case of functionalized olefins, heterogeneous catalysts have usually not performed well [84,85]. Methyl oleate is the typical test substrate the following order of stability towards the ester functional group for the different SOM catalysts has been observed (based on the number of turnovers) Re W > Mo, which is similar to what has been described for related homogeneous systems. In the specific case of Re, 900 TON can be reached, while TON for other Re-based heterogeneous catalysts do not exceed 200 [79,84]. 

In the first part of this activity, you will prepare a polyester. As the name polyester implies, this polymer contains many ester functional groups. One technique for preparing an ester is by the reaction of a carboxylic acid with an alcohol. RCOOH + R OH —> RCOOR + H20... 

We have attempted the low temperature formation of Grignard reagents containing nitrile, ketone and ester functional groups. These reactions were largely unsuccessful, except in the case of 8-bromooctanenitrile. 

If we now link each of the hydroxyl groups to a carboxyl group of a fatty acid, we get a triglyceride that possesses three ester functional groups ... 

Methyl esters are always the preferred substrates, conversions being lower with, for example, ethyl esters. Functional groups such as nitro, methoxy, alkenyl and pyridyl are compatible with the reaction conditions. Diesters can only be effective if bis-transesterification is desired, when an excess of the alcohol (e.g., 3-5 equiv) is necessary. Methyl acrylate tends to polymerize under the reaction conditions, but the use of an excess of the ester (3-5 equiv) and lower temperatures (-10°C) allows efficient isolation of the required ester. 

The local anesthetics can be broadly categorized on the basis of the chemical nature of the linkage contained within the intermediate alkyl chain group. The amide local anesthetics include lidocaine (7.5), mepivacaine (7.6), bupivacaine (7.7), etidocaine (7.8), prilocaine (7.9), and ropivacaine (7.10) the ester local anesthetics include cocaine (7.11), procaine (7.12), benzocaine (7.13), and tetracaine (7.14). Since the pharmacodynamic interaction of both amide and ester local anesthetics with the same Na" channel receptor is essentially idenhcal, the amide and ester functional groups are bioisosterically equivalent. However, amide and ester local anesthetics are not equal from a pharmacokinetic perspective. Since ester links are more susceptible to hydrolysis than amide links. 

Certain functional groups in drug molecules are prone to chemical degradation. Drugs with an ester functional group are easily hydrolysed e.g., aspirin is easily hydrolysed to salicylic acid. Similarly, many drug molecules are susceptible to oxidation because of certain oxidizable functional groups, e.g. alcohol. 

Alcoholysis of nitriles, of ortho and thio ortho esters (transesterification), and of halides is the most common method of preparing the ortho ester functional groups (see Eqs. 2-7). A less practical method is the addition of alcohols to ketene acetals. The latter method is used only when the other methods are not found applicable to the synthesis of specially substituted mixed ortho esters. 

VAAR [Structure (5.3)] contains oxygen, through its alcohol and ester functional groups, which can react with ingredients in the pyrotechnic formulations to produce additional energy. In addition, it has many other highly desirable characteristics as a pyrotechnic binder (i) it comes in the liquid form and thus it is simply... 

A typical fat molecule, also known as a triglyceride, is the combination of one glycerol unit and three fatty acid molecules. Note that this reaction involves the formation of three ester functional groups. 

React for 30 min to create the SASD derivative, coupled through the NHS ester functional groups of the cross-linker onto available amine groups of the protein (forming amide bonds). 

ABNP is soluble in DMF. Insulin labeling was done in DMF water at a ratio of 9 1. For molecules not soluble in organic solvent, such as proteins, the trifunctional may be dissolved in DMF and a small aliquot added to an aqueous reaction medium. The nitrophenyl ester functional group can be coupled to amine groups at alkaline pH (7— 9) and in buffers containing no extraneous amines (avoid Tris). Unfortunately, ABNP is not commercially available at the time of this writing. 

A-2. Both waxes and fats are lipids that contain the ester functional group. In what way do the structures of these lipids differ ... 

Esters are compounds that are commonly formed by the reaction of oxygen-containing acids with alcohols. The ester functional group is 0... 

Example APIs containing carbamic ester functional groups with the potential for hydrolysis are loratadine (Fig. 12) and pipazetate (18). 

ArN02 ArNH2.1 Aryl nitro compounds are reduced to arylamines by Ni2B at 40° in 3N HC1 or 15N NH4OH in 80-96% yield without effect on alkene, keto, nitrile, amide, carboxyl, or ester functional groups. Nitroso-, azoxy-, azo-, and hydrazobenzene are reduced to amines under the same conditions. 

The route described by Hoffmann-La Roche scientists in 1995 was designed to make use of the drug substance 5-DFCR (10) to prepare capecitabine in a few steps without multiple protection/deprotection transformations.19 In this process, 5 -deoxy-5-fluorocytodine (10)24 27 was added to three equivalents of -pentyl chloroformate and pyridine in methylene chloride while maintaining an internal temperature below -5 °C, ultimately providing the tris-acylated cytodine adduct 26 in a 92% isolated yield. Removal of the two ester functional groups by selective hydrolysis with aqueous sodium hydroxide in methanol at -10 °C for a short time followed by adjustment to pH5 with concentrated HCI provided the crude carbamate 1 in quantitative yield. Purification of... 

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